1、定义两个，公共属性。
   public string lblText{get;this.lable.text = value};
   
   public string lblText2{get;this.lable2.text = value};
   
   然后 this.textbox.text = lblText;

------解决方案--------------------

控件1：
C# code

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Drawing;
using System.Data;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace WindowsFormsControlLibrary1
{
    public partial class UserControl1: UserControl
    {
        public UserControl1()
        {
            InitializeComponent();
        }

        private string text1;

        public string Text1
        {
            get { return text1; }
            set 
            { 
                text1 = value;
                this.label1.Text = text1;
            }
        }

        public  delegate void myDelegate(eventData e);
        public  event myDelegate btClick;

        private void button1_Click(object sender, EventArgs e)
        {
            this.text1 = this.textBox1.Text;//单点击按钮时
            eventData _eventdata=new eventData();
            _eventdata.tempData=this.Text1;
            if (btClick!=null)
            {
                btClick(_eventdata);
            }
        }
    }

    public class eventData : EventArgs
    {
        public string tempData;
    }
}